A gas turbine engine generally includes a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section progressively increases the pressure of compressed air entering the gas turbine engine and supplies the compressed air to the combustion section. The compressed air and a fuel (e.g., natural gas) mix within the combustion section and burn in a combustion chamber to generate high pressure and high temperature combustion gases. The combustion gases flow from the combustion section into the turbine section where they expand to produce work. For example, expansion of the combustion gases in the turbine section may rotate a rotor shaft connected to, e.g., a generator to produce electricity. The combustion gases then exit the gas turbine engine via the exhaust section.
The combustion section may include one or more fuel nozzles. In particular embodiments, the one or more fuel nozzles may be bundled tube fuel nozzles, which premix the fuel and the compressed air upstream from the combustion chamber. In this respect, each of the bundled tube fuel nozzle assemblies generally includes a forward plate, an aft plate, and an outer sleeve, which collectively define a fuel plenum body. A plurality of tubes extends through the forward plate, the fuel plenum body, and the aft plate. In operation, a portion of the compressed air flows through a passage defined by each of the tubes. A portion of the fuel from the fuel plenum is injected into each tube (e.g., via a fuel port in each tube) for premixing with the compressed air therein. The fuel and compressed air mixture then flows through the passages in each of tubes to the combustion chamber.
In some embodiments, the tubes extend downstream from the aft plate. A cap plate located downstream from the aft plate defines a plurality of cap plate apertures through which the plurality of tubes extends. Because the downstream ends of the tubes are free to shift slightly in a radial direction, aligning each of the plurality of tubes for positioning within one of the plurality of cap plate apertures is a time-consuming and expensive process.